<!DOCTYPE html>
<html lang="en">

<head>
    <meta charset="UTF-8">
    <meta http-equiv="X-UA-Compatible" content="IE=edge">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <title>Document</title>
    <script src="https://cdn.jsdelivr.net/npm/vue@2.6.10/dist/vue.js"></script>
</head>
<style>
    .one {
        width: 100px;
        height: 100px;
        background-color: aqua;
    }

    .two {
        width: 100px;
        height: 100px;
        background-color: hotpink;
    }

    .three {
        width: 100px;
        height: 100px;
        background-color: yellowgreen;
    }
</style>
<body>
    <div id="APp">
        <div :class="className"></div>
        <div :class="isActive?'active':''">test active</div>
        <div :class="{active:isActive}">test active</div>
    </div>
</body>
<script>
    const vm = Vue({
        el:"#app",
        data() {
            return {
                className: {
                    one: false,
                    two: false,
                    three: false
                }
            }
        }
    })
</script>
</html>